The present invention relates to a control apparatus for an electrically driven sewing machine with a stitch pattern producing device, and in particular to a control apparatus for the electrically driven sewing machine which allows a sewing operation to be effected with a desired pattern stitch.
There has been hitherto known a control apparatus for an electrically driven sewing machine which is composed of information storage means such as ROM or the like for storing predetermined stitch patterns, an electric signal generator device for generating electric signals related to rotational angular positions of a main shaft of the sewing machine, means for reading out the stitch pattern information from the information storage means in response to the generated electric signals, and a driver device for controlling the needle position and the cloth feed operation in dependence upon the stitch pattern information as read out, thereby to carry out the pattern stitches in dependence upon the stitch pattern information. For example, this type control apparatus for the electrically driven sewing machine is disclosed in U.S. Pat. application Ser. No. 376,780 entitled "Sewing machines stitch pattern generation from stitch data stored in static memory", filed July 5, 1973 by John W. Wurst and issued Dec. 24, 1974 as U.S. Pat. No. 3,855,956 and assigned to The Singer Company.
However, the hitherto known electrically driven sewing machine of the above described type has sufferred from many drawbacks. For example, in order to permit sewing operations with various stitch patterns, a memory device of a large capacity is required, involving high manufacturing and maintenance costs. Further, since the available stitch patterns are restricted to those stored in the memory device, it is impossible or at least difficult to perform the sewing operation with any given stitch patterns as desired by the user.